Driven by concerns over how the charred landscape left behind by the Fourmile Fire would affect her health, Anne Rice -- who lives along Fourmile Creek near Logan Mill Road -- had her well water tested shortly after the devastating fire was finally put out.

A year and a half later, Rice had her well, which is downhill from much of the burn area, retested. The results showed that manganese concentrations had increased 67 percent, aluminum 100 percent, copper 600 percent and zinc 700 percent. Chloride concentrations sykrocketed 1,000 percent.

"The results were disturbing," she said.

All the concentrations of metals and elements tested were below recommended drinking water limits, but the sharp increase still weighs on Rice's mind.

"I need to do some research and find out how they're going to impact me," she said.

Increased concentrations of heavy metals are not uncommon after wildfires, though the degree of the increase depends on the characteristics of the area burned. The Fourmile Fire burned more than 6,000 acres and destroyed 169 homes in September 2010.

Humans require trace amounts of some heavy metals, but in larger amounts, those metals can become toxic.

Dan Neary, a scientist at the Forest Service's Rocky Mountain Research Station in Flagstaff, Ariz., said heavy metals can come from a variety of sources after a wildfire.

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"There may be natural sources of heavy metals that just get mobilized in the fire. They could be in the vegetation, and the metals stay in the ash and they get leached," he said. "Or it could be coming out of the heavy metal content in houses."

The amount of heavy metals found in vegetation can be related to heavy metals in the soil and sources in the air from nearby mining operations.

However, Neary said it makes sense to be cautious about the results of heavy metal testing of residential wells. It's important, he said, to make sure that the testing methods before and after are actually comparable and that one testing method wasn't more sensitive than another.

Water that travels through the burn area -- above and below ground -- not only replenishes area wells but it's also used by people living in the Pine Brook Hills subdivision. The Pine Brook Water District diverts water from Fourmile Creek to help fill its reservoir. But water district manager Robert de Haas said they haven't seen troubling increases in heavy metal concentrations in their water.

"A lot of that is because we try to take water when the creek flows are higher, so we have the dilution factor," he said. "We really did not see any significant increases."

De Haas said the district's water quality may also be helped by the fact that the water from Fourmile Creek is heavily aerated at a transfer station in Sunshine Canyon, which may help oxidize some of the metals, and that the inflow of water from Fourmile Creek is on the opposite end of the reservoir from the outflow to the treatment plant.

"A lot of that stuff is probably dropping out in our reservoir, to boot," he said.

The U.S. Geological Survey is also testing surface water conditions in Fourmile Creek. The agency installed probes and automatic water samplers in the creek shortly after the fire. A final report on those results is not yet finished.

But the results of a study by students from Metropolitan State College of Denver confirms an increase in heavy metals and other elements in Fourmile Creek about a month after the fire was contained. The students collected water samples on a part of the creek that was above the burn area and on a section of the creek that had already flowed through the burn area.

They found increased concentrations of calcium, chlorine, magnesium, manganese, sodium, sulfur and potassium in the downstream samples, which the authors believe can be attributed to the fire. They also found increases in aluminum and iron, which they attributed to changes in the geology of the creek between the two testing sites.

Finally, the students measured increases in boron, bromine, barium, antimony and strontium, though they weren't certain about the origin of those chemicals. However, the students said some of the increases might be related to flame retardant used to contain the fire and some of the building materials that were incinerated.

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